# std::is_trivial

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< cpp‎ | types

Defined in header `<type_traits>` |  |
template< class T > struct is_trivial; |  | (since C++11) (deprecated in C++26)

`std::is_trivial` is a UnaryTypeTrait.

If `T` is a trivial type, provides the member constant `value` equal to true. For any other type, `value` is false.

If std::remove_all_extents_t<T> is an incomplete type and not (possibly cv-qualified) void, the behavior is undefined.

If the program adds specializations for `std::is_trivial` or `std::is_trivial_v`, the behavior is undefined.

### Template parameters

T | - | a type to check

### Helper variable template

template< class T > constexpr bool is_trivial_v = is_trivial<T>::value; |  | (since C++17) (deprecated in C++26)

## Inherited from std::integral_constant

### Member constants

value [static] | true if `T` is a trivial type, false otherwise (public static member constant)

### Member functions

operator bool | converts the object to bool, returns value (public member function)
operator() (C++14) | returns value (public member function)

### Member types

Type | Definition
`value_type` | bool
`type` | std::integral_constant<bool, value>

### Example

Run this code

    #include <type_traits>

    struct A { int m; };
    static_assert(std::is_trivial_v<A> == true);

    struct B { B() {} };
    static_assert(std::is_trivial_v<B> == false);

    // The following class shows why std::is_trivial(_v) may be a pitfall.
    class C
    {
    private:
        C() = default;
    };

    static_assert(std::is_trivial_v<C> == true);
    static_assert(std::is_trivially_default_constructible_v<C> == false);

    int main() {}

### Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR | Applied to | Behavior as published | Correct behavior
--- | --- | --- | ---
LWG 2015 | C++11 | `T` could be an array of incomplete class type with unknown bound | the behavior is undefined in this case

### See also

is_trivially_copyable (C++11) | checks if a type is trivially copyable (class template)
is_default_constructibleis_trivially_default_constructibleis_nothrow_default_constructible (C++11)(C++11)(C++11) | checks if a type has a default constructor (class template)

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